Were it me,(and it ain't) and money was not an issue, I would want one of the filters you have selected under each end of the tank. The filter you have chosen,(good choice) would probably handle the job, I tend to favor overfiltering my tanks. Some might call it over kill, but it has served me well.

I have tested my water and all of these seem compatible with each other and my water with the possible exception of the danios. My kh appears to be too low for these guys. I am getting a reading of 6 out of my tap and am unsure how that will change once I start cycling my tank with the driftwood, rocks and plants. I have read some in-depth coverage of ph readings but not so much on kh.

I have decided to include plants since the extra work appears to be worth it both for the look of the tank and also the benefits from having live plants.

A filter has also been chosen. I have settled on the Eheim Plus 2217-37. The manufacturer says this filter is good to 150 gallons or so. Is a secondary filter necessary or is this sufficient for the task at hand?

Any feedback on this is once again much appreciated.

The german blue rams as well as the gold variety, are truly beautiful little fish,, and the number of them you have selected may present a problem when and if a pair decides to breed. Rams are little warriors and are fearless in defending the place where they have decided to deposit eggs. A heavily planted tank will help ,but corys and raphael will no doubt draw the ire of these fish once eggs are laid. I am doubtful that the rams could do any real damage,but if attempting to raise the young appeals to you, then moving the pair to a tank of their own may be needed. I might were it me,, start out with two or three rams and see how things go. I feel I should also say,, rams do poorly in water that is not to their liking. They thrive in temp. of 82 to 84 degrees and don't seem to do well below these temperatures, This will possibly limit your selection of plants.There is a lot of literature out there on these fish ,and I would urge you to assimilate as much as you can stand. Good Luck!